A large number of patents exist in which certain turbo aero engine elements are heated or more frequently cooled by taking the air or gases from other portions of the machine via a derivation circuit. The aim is generally to provoke heat expansions or contractions on these elements so as to reduce the plays between the free ends of vanes of turbines or compressors and the walls in front of these free ends and limit any leaks and output losses.
The situation on revving up of the machine, for example on the take-off of an aircraft if the machine is a turbojet engine, does pose specific problems as the most significant heating, which is suddenly produced on account of increasing the flow of hot gas, concerns firstly the turbine vanes and peripheral portions of turbine disks adjacent to these vanes. As a result, a heat gradient forms on the turbine disks whose central portions only heat up slowly, and the original heat stresses which appear require that heavier turbine disks be designed than would otherwise be the case.